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Chemistry > Redox And Group 2 > Flashcards

Redox And Group 2 Flashcards

1
Q

Define oxidation (4)

A

Oxygen addition
Hydrogen loss
Electron loss
Increase oxidation number

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2
Q

Define reduction (4)

A

Oxygen loss
Hydrogen addition
Electron gain
Decrease oxidation number

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3
Q

Oxidation number

A

Measure of how oxidised an atom is

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4
Q

Oxidation number rules (9)

A

Simple ion = charge
Atom as pure element = 0
F = always -1
O = -2 (except F compounds)
Cl = -1 (except O/F compounds)
H = 1+ (except metal hydrides)
Group 1 = always 1+
Group 2 = always 2+
Al = always 3+

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5
Q

Sum of oxidation number rule (3)

A

Must be equal on both sides
Sum of ONs in a compound = overall charge
Quoted per atom not compound

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6
Q

Balancing redox equations using ONs

A

Identify atoms being O/R
Balance amount each is being O/R by
Don’t change O/R ratio
Total left/right charges, balance

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7
Q

Half equation electron placement

A

O = right
R = left

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8
Q

Half equations (5)

A

R or O
Feature electrons
2X —> ionic equ
Reversible (depends on other elements reactivity)

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9
Q

Ionic equations (4)

A

1 O, 1 R
Balance e no
Cancel common terms
H+ and OH- on same side —> H2O

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10
Q

Disproprotionation

A

Element in a species O and R simultaneously
Eg. 2Cu+ —> Cu + Cu2+

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11
Q

Ionic radius group 2 strand

A

Smaller up the group
Less electron shells
Less shielding
Electrons held tighter
Electrostatic attraction is stronger despite constant charge

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12
Q

Ionisation energy group 2 trend

A

Decreases down the group
More electrons, more electron shells
More shielding from positive nucelus
Outer electrons further from nucleus
Reduces attraction despite nuclear charge being constant
Easier to remove electrons

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13
Q

Reactivity trend group 2

A

Increases down the group
React by losing outer electrons —> Mg2+
Higher IEs, harder to do
Lower IEs = more reactive

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14
Q

Group 2 reaction with water trends

A

Make metal hydroxides and hydrogen
Be - doesnt react
Mg - very slowly reacts, ppte
Ca - steadily, ppte
Sr - fairly quick, clear solution
Ba - rapid, clear solution

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15
Q

Magnesium reaction with steam

A

Forms MgO rapidly
Bright white light
Hydrogen gas as it leaves tube (safety)

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16
Q

Group 2 react with oxygen trends

A

Mg - bright flame
Oxides are bases
React with water —> metal hydroxides/alkalis/OH-, more alkaline down the group
BeO - exception, insoluble
MgO - reacts slowly, MgOH insoluble

17
Q

Give a use of group 2 oxides

A

Agriculture, neutralise soil acids

18
Q

Group 2 chlorine reaction trend

A

BeCl2 - covalent, dative, Be electron deficient
Be more electronegative than rest of group 2, high polarising power

19
Q

Why do group 2 give off colour in a flame test

A

Energy absorbed from fame
Electrons move to higher levels (excited)
Colour seen when electrons fall back down, release energy as light
Difference in energy levels/wavelength determines colour
Electron transition

20
Q

Flame test method

A

Heat platinum/nichrome wire in roaring Bunsen flame until no colour is seen
Dip in conc HCl
Put in flame
Dip in conc HCl
Dip in metal compound
Put in flame

21
Q

Flame test results (Li, Na, K, Rb, Ce, Ca, Sr, Ba, Cu, Mg)

A

Li - Red
Na - Yellow
K - Lilac
Rb - Red/purple
Ce - Violet
Ca - Brick red
Sr - Crimson
Ba - Green
Cu - Turquoise
Mg - Colourless

22
Q

Test for ammonium ions

A

Cation
Doesn’t give off colour in a flame test
Add to NaOH
Warm
Ammonia gas —> damp red litmus —> blue

23
Q

Solubility trend group 2 hydroxides

A

Increases down the group
Reason…?

24
Q

Uses of MgOH

A

Sparingly soluble
Anti acids neutralise stomach
Laxative
Low OH- conc, not a health risk

25
Q

Group 2 double charged negative ion compound solubility trend

A

Decrease down group

26
Q

BaSO4 uses

A

Insoluble
Shows up on x ray
Toxic, safe as its insoluble

27
Q

Thermo stability group 2 trend

A

Extent to which something breaks down when heated
More thermally stable = more heat to break it down
Increases down the group
Group 1 more thermally stable than group 2, lesser charge, less distortion

28
Q

Group 2 polarising power trend

A

Ability of a positive ion to distort the anion electron cloud
Larger charge/smaller ion/higher charge density = greater pp
More distortion, less stability

29
Q

Group 2 carbonates thermal decomposition trends and observations

A

Decompose —> metal oxide and carbon dioxide
Increase thermal stability down the group
Limewater test for CO2
Test for aqueous acids, effervescence

30
Q

Group 2 nitrates thermal decomposition trends

A

Make metal oxide, nitrogen dioxide and oxygen
Thermal stability increases down the group

Chemistry (24 decks)

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